JP2934552B2 - Water injection diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a water-injected diesel engine.

[0002]

Nitrogen oxides in the exhaust gas of the Related Art Diesel engine (NO _X) to reduce, as a means of achieving together also reduce the exhaust black smoke and fuel consumption rate at the same time, the fuel and water from the same fuel injection valve It is said that a water injection diesel engine that injects the fuel into the cylinder is effective. FIG. 5 shows a configuration of a conventional fuel / water injection device for the engine.
In the figure, 1 is a fuel tank, 2 is a fuel supply pump, 3
Reference numeral 4 denotes a fuel injection pump, 4 denotes the same plunger, 5 denotes a plunger barrel, 6 denotes a discharge valve, 7 denotes a check pressure regulating valve provided on a bypass of the discharge valve 6, 8 denotes a fuel injection pipe, and 40 denotes a fuel injection valve. Reference numeral 9 denotes the main body, 10 denotes a nozzle, 11 denotes a needle valve, 12 denotes an oil reservoir, and 14 denotes a pressing spring of the needle valve 11.

[0003] Also, 19 is a water tank, 18 is a water supply pump, 17 is a water supply pipe (pump side), 16 is a water supply control valve, 15 is a water supply pipe (injection valve side), and 13 is the reverse of water supply. A stop valve prevents backflow of water to the control valve side. Reference numeral 20 denotes a control device for controlling a supply amount and a supply timing of water, which inputs a crank angle signal of the engine and a signal of other engine operating conditions, and outputs an open / close signal to the control valve 16 via a line 23. A fuel passage 22 is perforated in the main body 9 of the fuel injection valve 40 to allow the fuel injection pipe 8 and the oil reservoir 12 to communicate with each other. In addition, the main body 9 of the injection valve 40 has a feedwater inflow passage 2.
A check valve 13 is provided in the middle of the flow passage, and communicates with a junction 31 in the middle of the fuel passage 22 via a water passage 30 formed in a downstream portion of the flow passage. ing.

The operation of the above configuration is as follows. The water pumped by the water supply pump 18 from the water tank 19 is sent to the control valve 16 through the water supply pipe 17, and the control is performed during a stop period in which the plunger 4 of the fuel injection pump 3 is not performing fuel pumping. The valve 16 is maintained in the open state for a predetermined period via the control device, and a predetermined amount of water is supplied through the water supply pipe 15 to the water supply inflow passage 2 of the fuel injection valve 40.
It is sent to 1. At this time, if the opening pressure of the check pressure regulating valve 7 of the fuel injection pump 3 is P _R , the opening pressure of the water supply check valve 13 is P _P , and the opening pressure of the needle valve 11 is P _O , P _O > Since P _R , P _O > P _P , the supplied water passes through the water supply check valve 13 and flows from the water passage 30 into the fuel passage 22 through the junction 31. Due to this supply water pressure, the fuel upstream of the junction 31 in the fuel passage 22, that is, on the side of the fuel injection pump 3, is pushed back inside the injection pipe 8 toward the injection pump 3,
The check pressure regulating valve 7 is pushed open to flow back into the plunger barrel.

FIG. 6 shows the resulting situation. In the fuel injection valve 40, the volume V ₂ of the oil sump 12 and the confluence portion 31
The fuel is filled to the volume of (V ₁ + V ₂ ) which is the sum of the volume V ₁ of the fuel passage 22 from the oil reservoir 12 to the oil sump 12, and a predetermined amount is filled in the fuel passage 22 on the upstream side of the junction 31. Water is filled, and the fuel in the fuel passage 22 on the upstream side is again filled with fuel. Next, when the plunger 4 of the fuel injection pump 3 rises to pressurize the fuel, the pressure in the fuel injection pipe 8, the fuel passage 22, and the oil sump 12 rises and becomes higher than the valve opening pressure P _O of the needle valve 11. The needle valve 11 is opened. At this time, the water in the water passage 30 is not pushed back to the control valve 16 by the action of the check valve 13.

When the pressure of the fuel exceeds the valve opening pressure P _O of the needle valve 11, the fuel of the above-mentioned volume (V ₁ + V ₂ ) is first injected from the injection port 10, and then the water supplied by a predetermined amount is discharged. Is injected, and finally, the remaining amount of fuel is completely injected. That is, when the amount of total fuel injected once a Q _F, Figure 7
As shown in the figure, first, an amount of fuel Q _FP = (V ₁ + V ₂ ) is injected, then a predetermined amount of water Q _W is injected, and if the remaining amount of fuel is Q _FS , Q _FS = Q _F -Q _FP will be fired last. As a result, first, the ignition of the combustion stroke initial by the fuel injection Q _FP is performed reliably, Shirube引of air into the fuel spray is increased by the injection of water arguments that will Q _W, elevated and black smoke burn rate it is possible to reduce of the NO _X by the introduction of water into the combustion zone with reduced generation is achieved.

[0007]

However, the prior art described above has the following problems. That is, there is always supplied water in the passage to the check valve portion and the merging portion of the fuel injection valve 40, and the pressure becomes high when injected and returns to low when injection is completed. At the end of this injection, cavitation often occurs in the passage, and in the case of water, it has been experienced that the cavitation intensity is several times higher even at the same cavitation intensity as that of the fuel. The presence of water has been pointed out as a problem in the durability of the injection valve, and a solution has been required.

[0008] Although further reduction of the NO _X in the exhaust gas is obtained substantially in proportion to the injection quantity Q _W of water, too increase the Q _W with respect to the total injection quantity Q _F of fuel, the initial injection amount of the fuel The time interval between the injection of _QFP and the late injection amount _QFS becomes too wide, which results in poor combustion and unstable operation of the engine. Therefore, in order to obtain a reduction of the NO _X, it is necessary to take an approach that is capable of increasing the water injection amount Q _W without causing poor combustion.

[0009] An object of the present invention is to solve the above-mentioned problems, and by adopting a structure in which fuel and water are injected into the cylinder in a multilayered manner, poor combustion can be achieved even if the injection amount of water is increased. without incurring, NO _X in the exhaust gas is reduced by a large margin,
An object of the present invention is to provide a highly reliable water-injected diesel engine having excellent durability.

[0010]

A water injection diesel engine according to the present invention is a water injection diesel engine in which fuel and water are injected into a cylinder from the same fuel injection valve. A fuel injection pump provided, a fuel injection valve for injecting fuel and water, a fuel injection pipe communicating a first fuel passage in the fuel injection valve with the fuel injection pump, a fuel tank and the fuel injection A second fuel supply line communicating a second fuel passage in the valve, a water supply line communicating a water tank with an inflow passage in the fuel injection valve, and the water supply line and the second fuel supply line. An electromagnetic control valve for controlling the opening and closing of the fuel supply pipes, a control device for controlling the electromagnetic control valve via a line, and a junction between a water inflow passage in the fuel injection valve and a second fuel passage Check valve provided downstream of the section, and below the check valve Passage and said first fuel passage is characterized by comprising and a merging unit for merging.

[0011]

According to the present invention, since the above-described configuration and control are performed, the following operations are performed. That is, during the suspension period from the end of the fuel / water injection by pressurization from the fuel injection pump 3 to the injection in the next cycle, the electromagnetic control valve 16 for the water supply pipe and the electromagnetic control for the fuel supply pipe are controlled. The valve 116 is electronically controlled through a control device and is repeatedly opened and closed alternately a plurality of times. The functions of the check pressure regulating valve 7 in the injection pump 3 and the check valve 13 in the injection valve 40 are also used. The water flowing from the inflow passage 21 and the fuel flowing from the second fuel passage 121 into the injection valve are alternately fed into the first fuel passage 22 by a predetermined amount to form a multi-layer liquid column of fuel and water. You. Thus, when the injection pump starts operating, fuel and water are alternately injected into the cylinder in a multilayered manner. At the end of the multi-layer injection of fuel and water into the fuel passage 22, the fuel supply control valve 116 is operated to fill the flow path from the check valve section 13 through the downstream passage 230 to the junction 31 with fuel. You can keep.

[0012]

FIG. 1 shows the configuration of a fuel / water injection device according to an embodiment of the present invention. In the figure, reference numerals 1 to 31 are the same as those in FIG. 5 showing the configuration in the conventional technique, so that the description will be omitted, and the configuration added in the embodiment of the present invention will be described. Fuel is also supplied to the fuel injection valve 40 from the second fuel supply line. 118 fuel pressurization pump
The fuel is pressure-fed from the fuel tank 1 to the electromagnetic fuel control valve 116 via the fuel supply pipe 117 and passes through the fuel supply pipe 115 to the second fuel passage 121 formed in the injector body 9.
Flows into Reference numeral 131 denotes a junction between the water inflow path 21 and the second fuel passage 121, and reference numeral 230 denotes a check valve downstream passage, which joins the first fuel passage 22 at the junction 31. In addition,
The junction between the check valve downstream passage 230 and the first fuel passage 22 may be at the downstream of the oil reservoir 12 or the check valve 13 in addition to the present embodiment.

Next, the operation of the embodiment will be described. FIG. 2 shows the operation of the electromagnetic water supply control valve 16 and the electromagnetic fuel supply control valve 116 at that time. If the water supply control valve 16 is opened while the fuel injection pump 3 is stopped and the fuel supply control valve 116 is closed by the control of the control device 20, the water supply pump 18 and the water supply pipe ( Water is pumped to the water inflow passage 21 of the injection valve body 9 via the pump side 17, the water supply control valve 16, and the water supply pipe (injection valve side) 15. The pumped water pushes the check valve 13,
The fuel in this portion is pushed back to the injection pump side by pushing out the check pressure regulating valve 7 disposed in the fuel injection pump 3, and the downstream passage 230 of the check valve is filled with water.

Subsequently, when the water supply control valve 16 is closed and the fuel supply control valve 116 is opened under the control of the control device 20, fuel flows from the junction 131, and the water and fuel Is pushed to the injection pump side, and the fuel is filled into the fuel passage 22. Subsequently, the same is repeated a plurality of times with the fuel supply control valve 116 closed and the water supply control valve 16 opened, and finally the fuel supply control valve 116 is opened, and the fuel supply control valve 116 is opened downstream from the check valve portion 13. Fuel is injected through the passage 230 to the junction 31 with the first fuel passage 22. FIG. 2 shows the operation state of both control valves 16 and 116 during this time.

As a result, in the first fuel passage 22, FIG.
As shown in FIG. 2, an alternate multilayer liquid column is formed as shown in fuel (white portion) -water (black portion) -fuel-water. When the fuel injection pump 3 operates to start injection, fuel and water in the oil sump 12 and the fuel passage 22 are injected by opening the needle valve 11, but at this time, as shown in FIG. since There will be injected in multi-layered alternately, there is no risk that the combustion becomes unstable even when a lot of amount of injected water into the spray to reduce the nO _x in the exhaust gas. Further, only the fuel remains in the portion of the fuel injection valve where the high pressure acts, so that the same durability as in the related art can be maintained.

[0016]

According to the present invention, in a water-injection diesel engine in which fuel and water are injected from the same fuel injection valve, the fuel and water are injected in a multi-layered form instead of the conventional water injection. Thus, even if the injection amount of water is greatly increased, the fuel is injected in a multilayer structure in the middle, so that the combustion does not become unstable. As a result, it is possible to increase the water injection amount becomes possible without causing poor combustion engine, to obtain a greatly reduction effects of the NO _x in the exhaust gas corresponding to the increase of the water injection quantity, durability It is possible to provide a reliable engine with high reliability.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fuel / water injection device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the operation of an electromagnetic water supply control valve and an electromagnetic fuel supply control valve in FIG. 1;

FIG. 3 is a detailed configuration diagram of a fuel / injection valve in FIG. 1;

FIG. 4 is an explanatory diagram of a fuel / water injection situation related to FIGS. 1 to 3;

FIG. 5 is a configuration diagram of a fuel / water injection device according to a conventional technique.

FIG. 6 is a detailed structural view of a fuel / injection valve in FIG. 5;

FIG. 7 is an explanatory diagram of a fuel / water injection situation related to FIGS. 5 and 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel tank, 3 ... Fuel injection pump, 6 ... Fuel discharge valve, 7 ... Check pressure regulating valve, 8 ... Fuel injection pipe, 13 ... Check valve,
15 water supply pipe (injection valve side), 16 electromagnetic water supply control valve, 17 water supply pipe (pump side), 18 water supply pump, 19 water tank, 20 control device, 21
Feed water inflow passage, 22 ... fuel passage (first), 23 ... line, 3
DESCRIPTION OF SYMBOLS 1 ... Junction part, 40 ... Fuel injection valve, 115 ... Fuel supply pipe (injection valve side), 116 ... Electromagnetic fuel supply control valve, 117
... Fuel supply pipe (pump side), 118 ... Fuel pressurizing pump,
121: fuel passage (second), 131: junction, 230 ...
Check valve downstream passage.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F02M 43/00 F02M 25/02 F02D 19/12

Claims (1)

(57) [Claims] 1. A water injection diesel engine in which fuel and water are injected into a cylinder from the same fuel injection valve (40), wherein a non-return pressure regulating valve (7) is provided on a bypass of a fuel discharge valve. A pump (3), a fuel injection valve (40) for injecting fuel and water, a fuel injection pipe (8) communicating the first fuel passage (22) in the fuel injection valve with the fuel injection pump, A fuel tank (1) and a second fuel injection valve;
The second fuel supply pipes (117) and (115) communicating with the fuel passages (121) of the fuel tanks, and the water supply pipes () that communicate the water tank (19) with the inflow path (21) in the fuel injection valve. 1
7) and (15); electromagnetic control valves (16) and (116) for controlling opening and closing of the water supply pipe (15) and the second fuel supply pipe (115), respectively; Valve with line
3) a control device (20) for controlling the flow of water through the fuel injection valve, and a reverse device provided downstream of a junction (131) between the water inflow passage (21) and the second fuel passage (121). A water-injection diesel engine comprising a stop valve (13) and a junction (31) where the passage (230) downstream of the check valve and the first fuel passage (22) merge.